There is a long-standing and ongoing need for improvements in lighting fixtures designed especially for the purpose of providing architecturally distinctive indirect lighting treaments in both private and public buildings where it is desired to provide uniform illumination over a flat surface such as a wall, ceiling or floor, while subjectively concealing the light source, thus creating a restful artificially-lighted environment free of distraction and annoyance from extraneous high intensity direct light and glare.
Fluorescent lighting has become predominant in this field due to its high efficiency, reliability, economy and versatility.
Among the many existing indirect fluorescent lighting fixture configurations for "wall wash" effects, the category addressed by this invention utilizes a reflector of non-symmetrical concave cross-section having a trough region offset along one side, partially surrounding an elongated lamp, and concealing it from normal view, while projecting direct and reflected light thru an offset light-exit window in a pattern of light intensity distribution determined by the cross-sectional shape of the reflector and location of the lamp. Examples of such lighting fixtures are found in U.S. Pat. Nos. 4,383,289 to Lewen, No. 4,564,888 to Lewen et al, No. 4,517,631 to Mullins and No. 4,519,019 to Hall.
In a typical installation, a row of such lighting fixtures may be recessed into a ceiling a few feet out from a wall that is to be "washed". Two of the performance deficiencies to which this type of lighting is prone are: (a) non-uniform illumination, usually a noticeable decrease in illumination toward the lower portions of the wall due to the greater distance from the fixture and the sharper angle of light incidence and (b) a scalloping of the upper fringe of the illuminated area due to uneven combination of illumination from each of the adjacent fixtures.
Even when an optimum reflector shape has been developed to address items (a) and (b) above, many serious problems remain in designing the fixture for successful manufacture; for example, the need for a cost-effective, reproducible reflector configuration having a high-efficiency optical-quality surface, accurately shaped to the required special concave cross-sectional curvature, and having sufficient structural rigidity to maintain its shape.
A simple formed metal reflector is deficient both in surface quality and in rigidity, and the non-uniform curvature required precludes simple roll-forming. The use of extruded aluminum is a viable process providing acceptable rigidity, however, alloys suitable for extrusion inherently yield a very low grade reflective surface: attempting the required smoothing and polishing would be very difficult and costly, especially in view of the non-uniformity of reflective surface curvature. On the other hand, the special high-purity metal required for a good reflective surface would be unsuitable for the extrusion process, structurally weak and prohibitively expensive.
All exposed reflector parts and other fixture parts such as decorative trim must be designed for optical compatibility so as to minimize extraneous light reflections, light leaks or other anomalies which would detract from the fixture's elegance and effectiveness. In addition, for a recessed installation, the fixture requires an integral flush trim surround with no exposed fastenings such as screwheads, and must be made easy to install, securely retained in normal use, and yet easily accessed for service.
It is a primary object of the present invention to provide an improved lighting fixture of the fluorescent offset-reflector hidden-light-source wall-wash type capable of substantially uniform illumination of a nearby flat surface perpendicular to a mounting surface carrying a single fixture or multiple side-by-side fixtures.
It is a further object of this invention to provide in the configuration of the improved fixture a practical, easily manufactured and uniformly reproducible reflector assembly having an efficient high quality reflective surface, accurately shaped to provide a special designated cross-sectional concave curvature.
It is still a further object of this invention to provide a novel system of decorative trim framing and installation means which makes the reflector assembly easy to install, secure and attractive in normal use and readily accessable for service.
Still a further object is the development and definition of a unique sequence of steps in optimally manufacturing and installing the improved lighting fixture of this invention.
These objects have been achieved in the novel structure and method of manufacture of the improved lighting fixture of this invention hereby disclosed.